Total-internal-reflection elastic metasurfaces: Design and application to structural vibration isolation

Journal Article · 26 November 2018 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.5052538 · OSTI ID:1487421

Zhu, Hongfei ^[1]; Walsh, Timothy F. ^[2]; Semperlotti, Fabio ^[1]

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1. Purdue Univ., West Lafayette, IN (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

This letter presents the concept of the Total Internal Reflection metasurface (TIR-MS) which supports the realization of structure-embedded subwavelength acoustic shields for elastic waves propagating in thin waveguides. The proposed metasurface design exploits extreme phase gradients, implemented via locally resonant elements, in order to achieve operating conditions that are largely beyond the critical angle. Such artificial discontinuity is capable of producing complete reflection of the incoming waves regardless of the specific angle of incidence. From a practical perspective, the TIR-MS behaves as a sound hard barrier that is impenetrable to long-wavelength modes at a selected frequency. The TIR metasurface concept is first conceived for a flat interface embedded in a rectangular waveguide and designed to block longitudinal S₀-type guided modes. Then, it is extended to circular plates in order to show how enclosed areas can be effectively shielded by incoming waves. Given the same underlying physics, an equivalent dynamic behavior was also numerically and experimentally illustrated for flexural A₀-type guided modes. This study shows numerical and experimental evidence that, when the metasurface is excited at the target frequency, significant vibration isolation can be achieved in the presence of waves having any arbitrary angle of incidence. Furthermore, these results open interesting paths to achieve vibration isolation and energy filtering in certain prototypical structures of interest for practical engineering applications.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1487421
• Report Number(s): SAND-2018-9065J; 667160
• Journal Information: Applied Physics Letters, Vol. 113, Issue 22; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English